15. Trends are easier to detect when the signal-to-noiseratio is low.

a True

b False

Q2.16. Accurate temperature readings were impossible before theinvention of the modern thermometer. Consequently, climatologistscan not say much about how temperature varied over the pastmillenium.

a True

b False

Q2.17. Climatologists have examined a variety of data sets in aneffort to determine whether or not Earth's climate is changing.Which of the following statements accurately summarizes what theyhave found?

Check all that apply:

1 Earth's mean surface temperature has increased over the past150 years and the rate of change is accelerating.

2 Glaciers are retreating, arctic sea ice is declining, and theice sheets of Greenland and Antarctica are melting, all of whichsuggest Earth's cryosphere is being affected by warmertemperatures.

3 Sea levels are rising.

Q2.18. Although Earth's mean surface temperature has increasedover the past century, this warming has not been evenlydistributed. Which of the following statements about how the Earthhas warmed are true?

Check all that apply:

1 Sea surface temperatures have increased more than land-airsurface temperatures.

2 High latitudes have warmed more than low latitudes

3 .Polar regions have cooled.